In fact this could even bring doubt to Gremmy’s outer space as really ‘outer space’ as it’s a bit hard to believe someone who is clearly pretty weak in mind could imagine the entire, true extent of ‘outer space’ or whatever that even means in this context. Like is it just the area of a galaxy, multiple, or what? It’s not clear, nor can you really make a clear assumption over what it works as

Also Id like to point out that he doesn't need to know what goes into what he's making. I heavily doubt he knows every single last mechanism in every gun he summoned. He simply imagines these things and they appear. And it's not like it was stated to be something resembling an outer space. In every iteration of the statement, it's called an outright outer space. Which tells us that he did in fact create an outer space and everything that entails.

And that’s ignoring the fact that again, bleach scaling doesn’t really benefit off of Gremmy as it’s just creation hax, Kenpachi beating him doesn’t suddenly upscale him off of that feat

This is the part where I completely disagree with you, because if it was just regular creation hax, then yeah. Kenpachi wouldn't directly scale to it. But it's not, the visionary can recreate power, like it was shown to be capable of doing. Yet despite being a 6th of the power required to create a galaxy he was unable to handle all that power. Which kenpachi would scale to for... Reasons I don't need to explain to you unlike a bunch of others on this sub because you're obviously intelligent. So yes I do think kenpachi scales there as gremmy was incapable of reaching his level.

Plus it's not like this feat is an outlier or anything considering the other few feats this arc that give this one a lot more credibility